Agriculture urbaine

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En provenance du cours de École Polytechnique Fédérale de Lausanne

Villes africaines I: Introduction à la planification urbaine

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École Polytechnique Fédérale de Lausanne

Villes africaines I: Introduction à la planification urbaine

33 notes

Le cours permet d'apprendre les bases de la planification urbaine à travers ses dimensions techniques, environnementales, sociales, économiques et symboliques. Le cours parle uniquement des villes africaines et même si celles-ci ont valeurs d'exemple pour les ville du Sud, voire toutes les villes, nous nous efforçons à remettre les problématiques dans un contexte africain.

À partir de la leçon

Le futur des villes ou comment planifier

Faire face au défi climatique qui change nos manières de faire la ville.

Agriculture urbaine6:17

Changement climatique5:52

Rencontrer les enseignants

Jérôme Chenal
Dr
Faculté de l'Environnement Naturel, Architectural et Construit - ENAC

Today we'll talk about urban agriculture.

From the start, there are three questions.

When saying urban agriculture

it involves first and foremost acknowledging agriculture in cities.

It also involves planning spaces

and managing this activity.

In simple terms, urban agriculture is working the land

within the boundaries of a city, or the suburban area, most often.

It means taking advantage of the gaps, of unused land,

of everything that lends itself to agriculture.

Every possible resource is used: land, water,

and afterwards the markets to sell the products,

and all that happening within a city.

Urban agriculture appears to be an oxymoron,

two contradictory terms.

Why?

Because, on one hand, there is agriculture

strongly associated with rural areas, where agriculture is done,

and on the other hand the urban world,

which by definition is not rural, and so should not have agriculture.

The conventional definitions of cities

do not take agriculture into account.

There are also many people who are strongly opposed

to any agriculture within cities.

Why?

Because these activities should not take place

within the city boundaries.

Then, there is the opposite point of view,

acknowledging the vital importance of urban agriculture

for African cities today

and taking it into account in the planning process.

We'll see that there are some vexed issues

when planning agriculture within city boundaries,

one of them being land ownership,

but the social stakes are very high when it comes to urban agriculture.

Agriculture encompasses social aspects,

issues of space, of resources, of risks associated to it.

Let's go through every item one by one.

First, the social issue.

Extremely important in social terms:

it's a source of income that is not insignificant

for families that are, most of the time, the most vulnerable.

There is a question of empowerment behind this,

at least for some populations:

feeding oneselves,

even being able to sell some of their produce to make a bit of money.

It does have an impact to be considered on employment.

The issue of space is extremely important.

Why?

Because agriculture requires space.

Except for Cuba, where during the Special period

every flower pot was turned into a micro field planted with something

and every possibility to grow something in the city was seized,

the usual pattern is to use suburban lands.

Hence the question of space:

will I choose to build dense housing

or choose a more spread-out pattern

leaving room for agricultural production, meaning income generation?

This is one thing.

The second thing is that the denser a city,

the more pressure there is on land prices.

At some stage, prices are so high that it doesn't make any sense anymore

to grow a few vegetables, and it drives people even further.

The issues at stake here

is the opposition between spread-out cities and compact cities,

the issue of land use, land speculation,

but also simply of land markets, which, in most of the countries

and cities we are dealing with, are open markets,

meaning they fluctuate according to several factors,

but governments do not have the power

to regulate land prices, which poses a real problem

leading to pressure being put on urban agriculture.

Let's move now to the issue of resources.

Water is necessary.

Not only is there a need for a sufficient amount of water,

but this water needs to be good enough, too.

We'll see the potential health problems associated with urban agriculture.

The main health hazard

is that most of the time waste water is used.

Waste water are good in that they fertilize soils,

but there are also a certain number of germs which are pollutants

and will pass into the plants

and in turn into humans.

So, there is the issue of water quantity

and also of water quality, with a caveat regarding waste water

which can become a time-bomb.

It's both a fertilizer and a potential health hazard

in areas with urban agriculture.

These are just a few quick elements about urban agriculture.

There is much more to say, but we won't go further today.

I would just want you to bear in mind

that there is an indisputable use, a social use, to urban agriculture

but that it should be well thought through

depending on the density pattern you choose,

on the transportation options, or lack thereof,

and, in the end, on the ability to retain ownership

over a piece of land in times of growing land use pressure

in African cities.

In this week's classes where we start to see how to plan,

we realize there is a certain number of elements to take into account

and that these elements don't always go in the same direction.

Which means there will be choices to make,

between the different options, the different patterns:

spread-out cities with room for agriculture,

which is very good for climate change in tropical areas,

but on the other side in terms of public transportation,

of increased commuting, of the ozone layer,

since it is what it comes down to, it should be avoided at all cost.

A dense city pattern is good

but it means there is no room for urban agriculture,

which eliminates part of the resources.

What it all comes down to is that there is no panacea.

But one must be aware of the need to make judgment calls

between those elements that must be factored in

in our planning of future cities.

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